Life support system

ABSTRACT

A life support system includes a refuge housing and a cooling system. The cooling system, which has a supply of liquefied gas and a cooling circuit, is operatively associated with the refuge housing. The supply of liquefied gas is operatively associated with the cooling circuit that contains a heat exchanger, a fan motor and a fan operatively associated with the fan motor. A conduit connects the heat exchanger to the fan motor that is driven by waste gas generated through a phase change of the liquefied gas in the heat exchanger.

CROSS-REFERENCE TO RELATED APPLICATION

Applicants claim priority under 35 U.S.C. 119(e) to provisional application No. 61/098,538, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a life support system. Specifically, the present invention is for a life support system including a self-operating cooling system, for a refuge in an emergency.

2. Background Information

Unexpected explosions, accidents and other emergency situations can occur in a wide variety of industrial environments, such as a mine, a petroleum refinery, a chemical plant, a sugar refinery and the like. In these situations, the ambient air can suddenly become unbreathable due to lack of oxygen and presence of toxic gases, including carbon monoxide (CO) and carbon dioxide (CO₂). Refuges offer a contained area of relative protection while awaiting rescue. However, a rescue effort may take many hours if not many days. Often, the refuges have a limited life support system for supporting the people in the contained area and may not be able to deal effectively with buildup of CO₂ and CO. Furthermore, the limited life support system is not compliant with evolving safety standards. In addition, some existing life support systems depend on power systems that may be cumbersome or unsafe to use in the emergent circumstances.

In view of the above, there exists a need for an improved life support system without conventional power sources. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.

BRIEF SUMMARY OF THE INVENTION

In accordance with one embodiment of the present invention, a life support system comprises a refuge housing and a cooling system operatively associated with the refuge housing. The cooling system has a cooling circuit and a supply of liquefied gas operatively associated with the cooling circuit. The cooling circuit comprises a heat exchanger, a fan motor and a fan operatively associated with the fan motor, and a first conduit connecting the heat exchanger to the fan motor. The fan motor is driven by waste gas generated through a phase change of the liquefied gas in the heat exchanger.

In another embodiment, a cooling system of the present invention comprises at least one tank of liquefied gas; a cooling circuit connected to the at least one tank by a supply conduit for supplying the liquefied gas to the cooling circuit, the cooling circuit comprising a heat exchanger configured to convert the liquefied gas to waste gas, a fan and a fan motor powered by the waste gas to turn the fan; a delivery unit having a fan port and at least one air port, the delivery unit housing the heat exchanger, the fan and the fan motor; and the fan motor and fan being configured to draw air through the at least one air port and through the heat exchanger and blow cooled air out the fan port.

The present invention also provides a method of cooling a confined area without a conventional power source. The method comprises evaluating a thermodynamic property of the confined area to calculate a result; providing at least one tank of liquefied gas; using the result to set a first pressure for the at least one tank; supplying a cooling circuit with liquefied gas from the tank at the first pressure, the cooling circuit comprising a heat exchanger; causing the liquefied gas to expand, resulting in expanded liquefied gas; allowing the expanded liquefied gas to convert to waste gas in the heat exchanger; using waste gas to turn a fan, thereby drawing air from the confined area across the heat exchanger, creating cooled air; and using the fan, blowing the cooled air into the confined area.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 illustrates the framework of a mine refuge housing and the contents therein;

FIG. 2 is a perspective view of the mine refuge housing in FIG. 1;

FIG. 3 is a top view of the mine refuge housing in FIG. 1 with the roof removed;

FIG. 4 is another embodiment of a mine refuge housing with life support elements according to the present invention therein;

FIG. 5 is a top view of another embodiment of a mine refuge housing in a cross-cut in a mine;

FIG. 6 is a top view of a collapsible mine refuge housing in a cross-cut in a mine;

FIG. 7 is a partial cross-section of the mine refuge housing in FIG. 1 taken along line 7-7;

FIG. 8 is a perspective view of a CO₂ scrubbing system and an air mover assembly in accordance with the present invention;

FIG. 9 is a perspective view of the air mover assembly in accordance with the present invention;

FIG. 10 is partial perspective view of the power supply and blower fan of the air mover assembly in accordance with the present invention;

FIG. 11 is a partial perspective view of the interior of the power supply in accordance with the present invention;

FIG. 12 is a schematic diagram of a cooling circuit for a self-operating cooling system in accordance with the present invention;

FIG. 13 is a perspective view of an embodiment of a tank in the cooling circuit in accordance with the present invention;

FIG. 14 is a partial perspective view of an interior of the tank of FIG. 13 in accordance with the present invention;

FIG. 15 is a top perspective view of a delivery unit with a cross section of a safety ring to show an interior of the delivery unit in accordance with the present invention;

FIG. 16 is a top perspective view of the interior of the delivery unit of FIG. 15 with upper components removed;

FIG. 17 is a side perspective view of the delivery unit in FIGS. 15 and 16 that is enclosed with a removable lid;

FIG. 18 is a partial cross-section of the delivery unit in FIGS. 15-17 in accordance with the present invention;

FIG. 19 is a partial cross-section of a self-operating cooling system in accordance with another embodiment of the present invention;

FIG. 20 is a front view of an embodiment of the delivery unit of the self-operating cooling system;

FIG. 21 is a front view of a case for holding the delivery unit;

FIG. 22 is a perspective view of a tank array enclosure holding a tank array;

FIG. 23 is a plan view of a tank array;

FIG. 24 is a cross-section of the delivery unit of an embodiment of the self-operating cooling system of the present invention; and

FIG. 25 is a front view of the delivery unit.

DETAILED DESCRIPTION OF THE INVENTION

There is a need to provide a refuge where breathable air can be maintained so that it is cleared of CO, scrubbed of CO₂ and cooled. Such refuge allows workers to remain in a predetermined safe area sheltered from the oxygen (O₂) deficient and/or noxious atmosphere until they can be brought to safety. While it is possible to use the present invention in many environments subject to such events, embodiments of the present invention will be described in the context of an underground mine.

Life support system 1 of the present invention offers refuge for miners in an emergency. Life support system 1 of the present invention comprises mine refuge housing 2 and life support elements 4 associated with the mine refuge housing 2. Life support elements 4 comprise O₂ replacement system 12, CO₂ scrubbing system 14 (including air mover assembly 10) and self-operating cooling system 16.

Referring to FIGS. 1-6, mine refuge housing 2 may comprise various structures and may be made of various materials as long as the structures provide a sealed or substantially sealed environment in which life support elements 4 can support miners for a period of days until rescued. An embodiment of the present invention, in which mine refuge housing 2 comprises a fixed, non-collapsible structure, is shown in FIGS. 1-3.

Mine refuge housing 2 defines a chamber 78 for the miners. Chamber 78 comprises floor 80, sidewalls 82, 83, front wall 84, back wall 85 and roof 88 that form a space in which miners can safely await rescue in an emergency. Side walls 82, 83 extend out from floor 80 and may contain portals or windows. A plurality of seats 92, forming a row, are located against sidewalls 82, 83, although other arrangements are possible. Additional storage for other components (e.g., purge air tanks 96, O₂ tanks 12 a, cartridges 6 described in further detail below) is provided under the seats 92, for example. Front wall 84 and back wall 85 are located at the ends of side walls 82, 83 and connect the floor 80, side walls 82, 83 and roof 88. As shown, floor 80 rests on skids 86, e.g. 6-inch I-beam skids. As a result, the mine refuge housing 2 may be easily moved. As shown, CO₂ scrubbing system 14 is located adjacent back wall 85. In the embodiment shown, front wall 84 receives air lock 94 that extends through front wall 84 and into chamber 78. As shown, air lock 94 also extends out of mine refuge housing 2 and into the mine environment, serving as an interface between a noxious atmosphere in the mine environment and a purged atmosphere in the chamber 78. Other configurations for air lock 94 are also possible as would be familiar to one having ordinary skill in the art after becoming familiar with the teachings of the present invention.

Air lock 94 can hold up to six miners, for example, and is used to purge CO and other noxious gasses, thereby limiting the amount of noxious gas brought into chamber 78 as the miners enter. Air lock 94 comprises one or more purge air tanks 96 of compressed breathable air used to purge the air lock 94 of noxious gasses. In the embodiment shown, the purge air tanks 96 are “T” sized bottles. In operation, miners enter the air lock 94, and shut exterior door 97. The miners then open all the valves (not shown) on the purge air tanks 96, open a flow valve (not shown) to release breathable air through a first manifold and then a discharge manifold (that acts in part as a muffler) into air lock 94 in a volume of up to three times the volume of the air lock 94 for up to 90 seconds. When the pressure builds up in air lock 94, the air is purged to the outside by pressure relief valves (not shown). In the embodiment shown, the pressure relief valves do not allow the pressure in the air lock to exceed about 62.3 pascals (Pa) (0.25 inches of water). After the purge is complete, the miners then can open interior door 98 and proceed into chamber 78 of the mine refuge housing 2. Preferably, there are enough purge air tanks 96 for up to thirteen purges.

Chamber 78 may further comprise storage compartment 90 for non-perishable consumables, potable water and toilet 99. Storage compartment 90 optionally has shelves 90 a for storage. Toilet 99 may be a PETT® compact dry toilet system with a disposal box, for example. Toilet 99 shown in this embodiment is commercially available from Phillips Environmental Products, Inc. of Belgrade, Mont.

FIGS. 4-6 illustrate alternate embodiments of mine refuge housing 2. FIG. 6 illustrates an alternate embodiment wherein the mine refuge housing 2 is a collapsible structure. The mine refuge housing 2 and life support elements 4 of the present invention provide a breathable and cooled environment (e.g., cooled, breathable air) for up to 27 miners for at least about 96 hours, for example. Other examples of the mine refuge housing 2 as a tent or collapsible structure can be found in WO 2005/052319 and US 2007/0199244. These various structures for mine refuge housings 2 all provide a place for miners to seek refuge in an emergency until rescued. Life support elements 4 enhance the environment within these various structures, as in explained more detail below.

The life support system 1, including the mine refuge housing 2, may be logically situated based on the type of environment in which it is being used. Thus, in the embodiments illustrated in FIGS. 4-6, for an underground coal mine, for example, the mine refuge housing 2 is located relatively close to a working face (e.g., about 1000 feet from the furthest extent of a belt conveyor system, or a belt tailpiece). More specifically, the mine refuge housing 2 is placed in a cross-cut in the mine situated between two pillars P on the one hand, and between two entries E on the other hand, and oriented so that a back of the mine refuge housing 2 is near a stopping S.

Life support elements 4 provide the necessary energy and devices to accomplish critical functions inside the confines of the mine refuge housing 2. Since air 64 inside the mine refuge housing 2 is finite and must be reused, life support elements 4 comprise O₂ replacement system 12 and CO₂ scrubbing system 14. O₂ replacement system 12 replaces O₂ that is depleted and CO₂ is removed through CO₂ scrubbing system 14, both of which operate to maintain the finite amount of air in chamber 78 of the mine refuge housing 2 as breathable air. As will be explained in more detail below, life support elements 4 also comprise self-operating cooling system 16 that cools the temperature of the air 64 in the chamber 78 to a tolerable degree. CO removal and emergency back-up power for emergency communication systems may also be provided.

Referring to FIG. 7, the O₂ replacement system 12 includes a plurality of medical grade oxygen bottles 12 a that are connected together via tubing 12 b and regulators 12 c to provide O₂ into the finite amount of air 64 in chamber 78 of the mine refuge housing 2 at about 0.5 L/min/person, for example. The O₂ replacement system 12 can be arranged in a space-saving arch over the CO₂ scrubbing system 14 as shown in FIG. 7, or in any other manner as would be obvious to one of ordinary skill in the art after becoming familiar with the teachings of the present invention.

The CO₂ scrubbing system 14 of the present invention actively scrubs CO₂. This is in contrast to prior CO₂ scrubbers that passively scrub CO₂ in the form of a curtain. In the present embodiment, the CO₂ scrubbing system 14 comprises a bed 14 a with legs 14 b. One or more chemical cartridges 6 containing soda lime, for example, are positioned in apertures 14 c in bed 14 a to remove or absorb CO₂ from the atmosphere inside chamber 78 of mine refuge housing 2. Soda lime chemical cartridges 6, sold under the name SOFNOLIME®, are commercially available from Molecular Products Ltd. of Essex, England.

In one embodiment of CO₂ scrubbing system 14 as shown in FIGS. 7-10, air mover assembly 10 draws air through the CO₂ scrubbing system 14 and blows treated air out for circulation in chamber 78 of mine refuge housing 2. Air mover assembly 10 may comprise blower fan 20 that may be a centrifugal blower powered by power supply 18, intake tube 22 and exhaust tube 24 both of which are connected to blower fan 20. Power supply 18 is disposed under the CO₂ scrubbing system 14. In another embodiment of the CO₂ scrubbing system 14 described below in more detail, no power supply 18 is required.

The blower fan 20 circulates air 64 about the chamber 78 of mine refuge housing 2. In addition, the blower fan 20 pulls air through the CO₂ scrubbing system 14. The blower fan 20 has inlet 20 a for drawing in air 64 and outlet 20 b that blows out scrubbed air. Specifically, inlet 20 a is connected to outlet 14 d on the bottom side of the bed 14 a via intake tube 22; outlet 20 b is connected to exhaust tube 24 in order to circulate scrubbed air in the chamber 78. In addition, tubing 12 b from O₂ replacement system 12 is connected to exhaust tube 24 to mix O₂ with the scrubbed air. Thus, blower fan 20 causes CO₂ to be scrubbed by drawing air 64 through the CO₂ scrubbing system 14, exhausts O₂ into the air 64 via the connection with the exhaust tube 24 and the O₂ replacement system 12, and propels the scrubbed air along with the O₂ into chamber 78 of mine refuge housing 2.

In the embodiment illustrated in FIGS. 7-11, power supply 18 provides power needed to run various devices located in the mine refuge housing 2, such as blower fan 20 or emergency communication systems (not shown). Power supply 18 comprises a permissible explosion-proof housing 26, one or more batteries 28, electric motor 30 electrically connected to the batteries 28 and a rotatable shaft 32 coupled to blower fan 20 and rotated by electric motor 30.

Explosion-proof housing 26 contains batteries 28, as well as electric motor 30 to which batteries 28 provide power. Explosion-proof housing 26 is preferably permissible in compliance with the regulations of U.S. Department of Labor, Mine Safety and Health Administration, 30 C.F.R. Part 18 (2007 and 2008) (“MSHA permissibility regulations”). Explosion-proof housing 26 is configured to maintain the batteries 28 and motor 30 in compliance with the MSHA permissibility regulations so that any spark or explosion is contained within explosion-proof housing 26 without propagating to the outside atmosphere, which may contain combustible gases. Explosion-proof housing 26 of the present invention has been approved as meeting the MSHA permissibility regulations.

The batteries 28 are preferably of the fiber gel type and, in addition to powering aspects of the life support elements 4, can be connected to and power various other electrical components needed while awaiting rescue, such as emergency communication systems (not shown). As used in the present embodiment, the batteries 28 are commercially available from NorthStar Battery Company LLC of Springfield, Mo. Fiber gel type batteries 28 are advantageous because off-gassing is minimal when charged and the charge can last for about 2 years. Referring to FIG. 11, the batteries 28 are strapped to the inside of explosion-proof housing 26 using stainless steel straps 29 that are bolted to both a floor and a wall of the explosion-proof housing 26. Terminals 28 a of the batteries 28 are connected to the motor 30 or other electrical components by connectors 28 b. To monitor and control the power supply 18, a volt meter, volt meter activator and/or a start-stop switch may be included at, on, or near explosion-proof housing 26.

Electric motor 30 is preferably a 24 V DC blower motor, powered by batteries 28. Electric motor 30 rotates rotatable shaft 32 to operate blower fan 20, the rotable shaft 32 extending from electric motor 30 through a wall in explosion-proof housing 26 (adjacent to blower fan 20) to blower fan 20. One or more bushings 32 a are disposed in the wall to rotatably support rotatable shaft 32. In the embodiment shown, bushings 32 a are permissible, self-lubricating brass bushings. Rotatable shaft 32 includes dodge couplers 32 b on either or both sides of the wall of explosion-proof housing 26. In addition, rotatable shaft 32 can be connected to various electrical-mechanical components, such as a compressor, pump or any device utilizing rotation, as desired.

Blower fan 20 pulls the air 64 through the CO₂ scrubbing system 14, specifically chemical cartridge 6. The resulting scrubbed air is blown through exhaust tube 24 and is mixed with O₂ from the O₂ replacement system 12.

Self-operating cooling system 16 will now be described in more detail. In an embodiment illustrated in FIGS. 12-18, self-operating cooling system 16 of the life support elements 4 controls the temperature in a confined area, such as a sealed or substantially sealed area. Examples of a sealed or substantially sealed area are areas of the chamber 78 of mine refuge housing 2, collapsible mine refuge housing (FIG. 6), campers, sleeper cabs, emergency make-shift rooms, or other rooms that require cooled air. In the context of the mine refuge housing 2, cooling is necessary because of the effects of heat and humidity in the confined space of chamber 78 on miners awaiting rescue. Self operating cooling system 16 is placed in chamber 78. Self-operating cooling system 16 of the present invention utilizes cooling provided by liquefied gas 40 to control temperature and reduce humidity.

In one embodiment, self-operating cooling system 16 comprises cooling circuit 34 that exploits the properties of liquefied gas 40 to cool the atmosphere in chamber 78. Self-operating cooling system 16 of the present invention can maintain an apparent temperature of about 34.4° C. (94° F.) or below, for example, in areas of the mine refuge housing 2 that are occupied by miners. In the embodiment shown, the self-operating cooling system 16 can reduce air temperature in the chamber 78 by about negative 12.2° C. to 6.7° C. (10° F. to 20° F.), for example, and also reduce the relative humidity. Thus, for purposes of the present invention, “liquefied gas” means a gas, gaseous compound or gaseous mixture converted to and maintained in the liquid phase by pressure or cooling, which boils at sufficiently low temperature to provide the required degree of cooling, examples of which may be liquid CO₂, liquid ammonia, liquid oxygen and the like. In the embodiments described herein, liquefied gas 40 can be liquid CO₂, liquid ammonia or the like. Liquid CO₂ is preferred since it is inert and capable of being stored in tank 36 with no loss to the outside. While, in other embodiments, cryogenic liquids, such as hydrogen, helium, nitrogen, oxygen, air and methane, may also be used, they may not be preferred in some embodiments described herein because they boil off during long periods of storage, causing loss.

Self-operating cooling system 16 further comprises tank 36 connected to the cooling circuit 34, delivery unit 38 housing some or all of cooling circuit 34, and liquefied gas 40 stored in tank 36 and used by the cooling circuit 34. Delivery unit 38 comprises heat exchanger 46, conduit 56, check valve 56, fan motor 60, fan 62 and exhaust conduit 66.

Referring to the embodiment illustrated in FIGS. 13 and 14, tank 36 comprises at least one pressure vessel to safely contain liquefied gas 40. Preferably, the tank 36 is certified and conforms to applicable standards. Tank 36 further includes housing 36 b that holds liquefied gas 40 inside the enclosure 36 a. Enclosure 36 a is generally cylindrical and can be about 20 inches in diameter and have a length of about 72 inches or larger. Tank 36 can be located either inside or outside of the mine refuge housing 2, as shown in FIGS. 1-6. Tank 36 may also comprise a tank array 176, as is explained in more detail below.

Referring to FIG. 12, cooling circuit 34 includes supply conduit 42 (that supplies liquefied gas 40 from tank 36), manual on-off valve 43 and expansion valve 44. Manual on-off valve 43 is provided along the supply conduit 42. Activation of the manual on-off valve 43 causes flow of liquefied gas 40 through enclosure 36 a and housing 36 b via supply conduit 42. The flow of liquefied gas 40 through supply conduit 42 is approximately 22.7 kilograms per hour (50 pounds per hour (lbs/hr)), for example. Expansion valve 44 reduces the pressure in supply conduit 42 from, in the case of liquid CO₂, approximately 4.83-5.52 megapascals (MPa) (700-800 pounds per square inch (psi)) down to approximately 1.38-2.76 MPa (200-400 psi), for example, depending on temperature.

In delivery unit 38, as shown in FIG. 12, heat exchanger 46 comprises a primary and secondary heat exchanger, e.g. first evaporator coil 46 and second evaporator coil 52. Thus, the flow of the liquefied gas 40 continues through supply conduit 42 to first and second evaporator coils 48, 52. First and second evaporator coils 48, 52 are in parallel and reduce pressure such that liquefied gas 40 begins to evaporate and convert to a gas. Once in a gaseous state, liquefied gas 40 flows out of heat exchanger 46 as waste gas and into conduit 54 through check valve 56 to fan motor 60, turning fan 62. Fan motor 60 is of the pneumatic type. Fan 62 draws air 64 through air ports 112 over first and second evaporator coils 48, 52 to create cooled air 264; fan 62 then blows the cooled air 264 into chamber 78 of mine refuge housing 2 without the use of electric or gasoline power or any separate power source. Exhaust gas from the fan motor 60 is expelled out of mine refuge housing 2 via exhaust conduit 66. Optionally, exhaust conduit 66 may be coupled to a muffler (not shown) to reduce noise. In another embodiment, exhaust conduit 66 or a branch off of conduit 54 may be directed to a second fan motor coupled to the blower fan 20, thereby running the CO₂ scrubbing system 14 without battery power or other conventional power source.

In another embodiment, cooling circuit 34 may also include a back pressure regulator, such as check valve 56, to maintain a sufficient back pressure in conduit 54 to ensure the liquefied gas 40 has been completely converted to and maintained in a gaseous state, i.e., ensure no solid or liquid exists at this stage.

In yet another embodiment, all of the valves and regulators in cooling circuit 34 can be electronically connected to and controlled by a microprocessor (not shown). Further, sensors (not shown), communicatively connected to the microprocessor, can be placed in the mine refuge housing 2 and the microprocessor can control the valves and regulators according to data from the sensors.

Self-operating cooling system 16 of the present invention does not require battery power or any auxiliary or secondary power to provide approximately up to about one ton (about 12,000 British Thermal Units (BTUs)), for example, of cooling capacity to cool air 64 in chamber 78 of mine refuge housing 2; it is self-operating. However, it will be apparent to one of ordinary skill in the art from this disclosure that a battery and electric motor can be used in place of fan motor 60 in appropriate circumstances.

Referring to FIGS. 15-18, an embodiment of delivery unit 38 of cooling circuit 34 is shown and will now be described in greater detail. Delivery unit 38 is made of polyethylene, for example, to provide a rust resistant, corrosion proof and impact resistant protective housing. Delivery unit 38 further provides a condensation surface by which cooling circuit 34 and delivery unit 38 act as a dehumidifier. It is expected that the air 64 in a sealed or substantially sealed mine refuge housing 2 will reach near 100% humidity. The cooling process performed by cooling circuit 34 not only provides cooled air 264, but also causes condensation on the inside or outside surfaces of delivery unit 38. Pan 67 is strategically placed under first and second evaporation coils 48, 52 to collect the condensate. The water in pan 67 can be routed to the exterior of the mine refuge housing 2 or used for drinking or other beneficial purposes.

In the embodiment shown in FIGS. 13-18, delivery unit 38 comprises first, second and third portions 70, 72, 74. The first, second and third portions 70, 72, 74 can be separable or form an integral unitary one-piece member. Each of the portions 70, 72, 74 are cylindrical and have an inner diameter that forms a space to contain various components of the self-operating cooling system 16. The inner diameter of the first, second and third portions 70, 72, 74 is about 76.2 centimeters (cm) (30 inches), for example, and the total length of the delivery unit 38 is about 152.4 cm (60 inches), for example. The first portion 70 is disposed on the second portion 72, which is disposed on the third portion 74 to form a barrel-like shape. The first portion 70 includes air flow efficiency collar 102 and discharge air safety ring 104 disposed within space 106 formed by an inner diameter of the first portion 70. Collar 102 is disposed above fan 62 and directs cooled air 264 out of delivery unit 38. Safety ring 104, located at top of the first portion 70, protects the components inside delivery unit 38 from the outside elements as well as protects miners from any potentially dangerous components inside delivery unit 38. Cooled air 264 flows through an inner diameter of safety ring 104. The inner diameter of the first portion 70 is substantially equal to an outer diameter of safety ring 104. The second portion 72 includes first and second ports 108, 110 that are formed in the wall of the second portion 72. First port 108 provides access to one or more components in the cooling circuit 34 and may be used as an outlet for exhaust conduit 66, while second port 110 includes a connection between supply conduit 42 and first and second evaporator coils 48, 52 in order to deliver liquefied gas 40 into delivery unit 38. Third portion 74 includes a plurality of air ports 112, as well as condensate collection port 114, formed in the wall of the third portion 74. Air ports 112 are each equipped with perforated rodent screen 112 a, allowing air 64 to flow through while keeping out rodents, bugs and other foreign objects.

In an embodiment shown in FIGS. 13-18, the operation of fan 62 creates negative pressure to draw air 64 through ports 112 and up the wall of the second and third portions 72, 74. Air 64 is then pulled through the evaporation coils 48, 52, where it is cooled, and then blown out of the delivery unit 38 as cooled air 264. Condensate collection port 114 provides access to pan 67 that collects the condensation formed during dehumidification. Water from the dehumidifying effect of the self-operating cooling system 16 can be drawn from condensate collection port 114 for drinking or other purposes. Alternatively, a conduit (not shown) connected to condensate collection port 114 can route the water to the exterior of the mine refuge housing 2. Delivery unit 38 is enclosed at the bottom by bottom portion 74 a of the third portion 74. First portion 70 has a removable lid 103 that closes the top of delivery unit 38 when not in use.

In yet another embodiment shown in FIG. 19, delivery unit 38 in the embodiment shown in FIG. 18 is attached to another embodiment of tank 36. That is, tank 36 is sized and shaped to form fourth portion 76 of delivery unit 38. Tank 36 is disposed underneath the third portion 74, supporting the weight of delivery unit 38. In addition, tank 36 has enclosure 36 a sized and shaped for attachment to delivery unit 38, as well as housing 36 b configured to hold liquefied gas 40. Tank 36 is connected to cooling circuit 34 by supply conduit 42. The first, second and third portions 70, 72, 74 of the delivery unit 38 and fourth portion 76 (containing tank 36) can form an unitary, integral one-piece unit. Alternatively, tank 36 can be detached from the delivery unit 38 for easy replacement when liquefied gas 40 is depleted.

In still another embodiment as illustrated in FIGS. 20-25, self-operating cooling system 16 of the present invention also supplies cooled air 264 to chamber 78 of mine refuge housing 2 without a conventional power source (i.e., electric, diesel, gas). Instead, self-operating cooling system 16 principally exploits heat of vaporization and gas generation from phase changes in liquefied gas 40 to supply the energy required to operate self-operating cooling system 16. Thus, self-operating cooling system 16 comprises tank array 176 (including tank array enclosure 180), delivery unit 138 and supply conduit 142 to connect tank array 176 to delivery unit 138. In the embodiments shown, self-operating cooling system 16 is placed in chamber 78 and is constructed of durable materials that can withstand the rigors of an underground mine environment and is engineered to withstand 0.103 MPa (15 psi) overpressure for 0.2 seconds.

As shown in FIGS. 22 and 23, tank array 176 comprises multiple high-pressure tanks 136 containing liquefied gas 40. The tanks 136 are connected via tank conduit 182 piped from one tank 136 to another tank 136 to enlarge the supply of liquefied gas 40. Supply conduit 142 is connected to tank array valve 178, which, when opened, allows liquefied gas 40 to flow from tank array 176 via supply conduit 142 to delivery unit 138. By connecting tanks 136 in this manner, a steady supply of liquefied gas 40 can be maintained for a period of days without having to change out the tanks 136. Tank array 176 as shown in FIG. 23 contains sufficient liquefied gas 40 to operate the self-operating cooling system 16 in a range of about 3,000 to about 18,000 BTUs (preferably, about 3,000 to about 12,000 BTUs) for up to about 96 hours. However, the size of tank array 176 (and the amount of liquefied gas 40) required in any given situation is a function of the thermodynamic factors affecting operation of the self-operating cooling system 16. These factors include, but are not limited to: construction of chamber 78 (e.g., material and location); chamber 78 dimensions, including cubic volume; maximum number of occupants; ambient conditions, including temperature; desired temperature; heat loss and gain (e.g., heat gain from actual number of occupants).

As shown in FIG. 22, tank array 176 is housed in tank array enclosure 180, which may be constructed of any materials suitable for the applicable conditions. For use in an underground mine environment in the embodiment shown, tank array enclosure 180 is fabricated from heavy duty steel, although other durable materials may be used. To allow tank enclosure 180 and tank array 176 to be moved, tank enclosure 180 is mounted on transportation skids 186. It is also possible to connect delivery unit 138 to individual tank 136 and operate self-operating cooling system 16 without tank array 176, as would be familiar to one of ordinary skill in the art. Pressure in tanks 136 may be maintained as relatively constant when installed in the tank enclosure 180 as part of tank array 176. The liquefied gas 40 is maintained in the tanks at about 5.17 MPa (750 psi) to about 5.52 MPa (800 psi), preferably about 800 psi, depending on temperature, specifically about 5.24 MPa (760 psi) at about 21.11° C. (70° F.).

Delivery unit 138 will now be described in more detail. Delivery unit 138 supplies cooled air 264 to lower the temperature in chamber 78 without a conventional power source, while using a single moving part—fan 162.

Delivery unit 138 is very small and portable, fitting into a case 170 that is fewer than 91.44 cm (three feet) long in its largest dimension, although the present invention should not be viewed as being limited in that respect. As shown in FIGS. 20-21, delivery unit 138 may be housed in case 170, comprising lid 170 a and trunk 170 b. Case 170 may also be equipped with retractable handle 171, with optional wheels (not shown), and is watertight, crushproof and dust proof. In the present embodiment, case 170 is model 1660NF commercially available from Pelican Products, Inc. of Torrance, Calif., USA. Delivery unit 138 may be operated without a conventional power source to supply cooled air 264 to chamber 78 of mine refuge housing 2 after first opening optional lock 172 and lifting lid 170 a. Gauges 174 for monitoring temperature and pressure, for example, may also be provided.

Delivery unit 138 comprises a combination of valves and regulators, heat exchanger 146, fan motor 160 and fan 162. FIGS. 24-25 illustrate cooling circuit 134, which will now be described for the embodiment shown. Supply conduit 142, carrying liquefied gas 40, is connected to delivery unit 138 at supply conduit connector 143, which includes an inlet orifice. In the embodiment shown, supply conduit connector 143 is connected to regulator 150 via a continuation of supply conduit 142. When liquified gas 40 enters regulator 150, its pressure is around 5.52 MPa (800 psi) at an ambient temperature of about 15.56° C. (60° F.) to about 32.22° C. (90° F.). After liquified gas 40 enters regulator 150, the pressure is reduced to between about 0.62 MPa (90 psi) and about 1.03 MPa (150 psi), allowing liquified gas 40 to begin to expand, but keeping liquefied gas 40 in a liquid state when liquefied gas 40 enters heat exchanger 146. Heat exchanger 146 comprises primary heat exchanger 148 and secondary heat exchanger 152, which are of the fin type and arranged in series. In the embodiment shown, primary heat exchanger 148 and secondary heat exchanger 152 are connected to supply conduit 142 via regulator 150 and expansion valve 144. Expansion valve 144 lowers the pressure of liquefied gas 40 from between about 1.03 MPa (150 psi) to about 0.66 MPa (95 psi) to between about 0.83 MPa (120 psi) to about 0.45 MPa (65 psi) preferably to about 1.03 MPa (150 psi) at about 21.11° C. (70° F.), thus allowing liquefied gas 40 to expand further and eventually convert to gas. When liquefied gas 40 leaves expansion valve 144 as expanded gas, it enters primary heat exchanger 148, substantially in a liquid phase. As liquefied gas 40 travels through primary heat exchanger 148, it continues its transformation to gas, entering secondary heat exchanger 152 (to which primary heat exchanger 148 is connected) substantially as a cold gas (e.g., between about negative 8.89° C. (16° F.) to about 1.67° C. (34° F.)), preferably about 1.11° C. (30° F.), or mixture of cold gas and liquid. As the liquefied gas 40 continues through secondary heat exchanger 152, it is further transformed, emerging from the secondary heat exchanger 152 substantially as a warm gas (e.g., between about 18.33° C. (65° F.) to about 29.44° C. (85° F.)), preferably about 21.11° C. (70° F.), which emerges from secondary heat exchanger 152 as waste gas carried by waste gas conduit 154. Waste gas conduit 154 carries waste gas to fan motor 160 to operate fan motor 160 thereby turning fan 162. In the embodiment shown in FIGS. 20-25, fan motor 160 is a pneumatic, oil-less fan that is commercially available from Gast Manufacturing, Inc. of Benton Harbor, Mich., USA (model no. NL22-FCW-4). Fan 162 is also commercially available; in an embodiment in which the life support system 1 is used in underground mine environment, the fan 162 may be made of non-sparking material (e.g., plastic, aluminum or brass) so that it will be permissible.

Waste gas conduit 154 is connected to fan motor 160 via back pressure regulator 156. As shown in the embodiment illustrated in FIGS. 20-25, back pressure regulator 156 regulates the pressure in the primary and secondary heat exchangers 148, 152 to ensure that liquefied gas 40 remains in either the gas or liquid state, while avoiding the triple point, or any other condition in which the liquefied gas 40 converts to a solid state, thereby freezing the operation of the heat exchanger 146. Exhaust gas not required to operate fan motor 160 is exhausted outside case 170 in exhaust conduit 166 through exhaust conduit outlet 168. In yet another embodiment, exhaust gas may be exhausted outside of mine refuge housing 2 in a manner that would be familiar to one of ordinary skill in the art. An advantage of doing so is to help make inert a mine atmosphere that may be noxious or explosive.

Self-operating cooling system 16 of the embodiment described in FIGS. 20-25 generates condensation when acting as a dehumidifier to reduce latent heat. Condensate may be collected and used or discarded in the manner previously described or in any way that would be apparent to one of ordinary skill in the art after becoming familiar with the teachings of the present invention.

Self-operating cooling system 16 may also be used to operate CO₂ scrubbing system 14 without power supply 18 which would also make the entire life support system 1 permissible. In that embodiment, waste gas conduit 154 may be connected to power air blower 20, thereby operating scrubber 14.

In an embodiment of the invention, all inlet orifices are of a first standard size and interchangeable; all outlet orifices are of a second standard size and interchangeable. The first standard size will only accept inlet orifice replacements and inlet connections and the second standard size will only accept outlet orifice replacements and outlet connections. Orifices and connections may also be of the quick connect type. By using interchangeable, quick connect type orifices and connections in the manner described, inlet orifices can easily be distinguished from outlet orifices, making the life support system 1 and life support elements 4 easier to assemble and components easier to replace. Thus, once a problem has been diagnosed, interchangeable orifices and quick connect type connections allow a defective component to be quickly removed and replaced in the field, even under exigent circumstances.

A method for cooling air 64 using self-operating cooling system 16 will now be described. First, the self-operating cooling system 16 has to be installed. As part of the installation step, thermodynamic properties of the environment in which the system will be installed are assessed. Based on those properties, pressure for the tanks 136 and tank array 176, as well as pressures for the expansion valve 144, regulator 150 and back pressure regulator 156, are set. Assessing the thermodynamic properties and setting such pressures may be done manually or automatically by implementing operating software along with sensors and microprocessors as described above. Individual valves for tanks 136 are left open; however, tank array valve 178 is closed. Supply conduit 142 is used to connect the tank array 176 with delivery unit 138. Once the self-operating cooling system 16 has been installed, no additional work or monitoring is required to be sure that it will be operational. The self-operating cooling system 16 does not need additional testing, maintenance or recharging to be ready for use.

Operating self-operating cooling system 16 requires initiating a flow of liquefied gas 40 to delivery unit 138, which is accomplished by opening tank array valve 178. Tank array valve 178 may be opened manually or automatically if self-operating cooling system 16 is equipped with the necessary hardware, software and sensors, as described above. Liquefied gas 40 is conveyed to delivery unit 138 by means of supply conduit 142, which enters delivery unit 138 via connection with supply conduit connection 143. As stated above, supply conduit 142 may be equipped with the standard inlet connector, which may be of the quick connect type, and supply conduit connection 143 may be equipped with the first standard size inlet orifice.

The method next provides that the pressure of the liquefied gas 40 be appropriately regulated to maintain the liquefied gas 40 in either the liquid phase or the gas phase depending on its location in the cooling circuit 134 of self-operating cooling system 16. The method then comprises maintaining the pressure in the range of around 5.17 MPa (750 psi) to around 5.52 MPa (800 psi), depending on temperature, preferably around 5.24 MPa (760 psi) at about 21.11° C. (70° F.) or the equivalent or other level required to keep the liquefied gas 40 in the liquid state before it enters regulator 150. The method further comprises allowing the liquefied gas 40 to expand by lowering the pressure to the range of around 1.03 MPa (150 psi) to around 0.45 MPa (65 psi), depending on temperature, preferably about 1.03 MPa (150 psi) at about 21.11° C. (70° F.) or the equivalent, or other appropriate pressure that permits the liquefied gas 40 to begin conversion to the gas phase. Expansion can be achieved by passing the liquefied gas 40 through regulator 150 and then expansion valve 144, resulting in expanded gas. Once the pressure of the liquefied gas 40 has been lowered, the liquefied gas 40 (now expanded gas) is converted to the gas phase by passing it through primary heat exchanger 148 and secondary heat exchanger 152 arranged in series. The method further comprises directing liquefied gas 40 as expanded gas into primary heat exchanger 148 in substantially liquid form. Further, as the liquefied gas 40 is passed through primary heat exchanger 148, it continues its phase change so that it leaves primary heat exchanger substantially in the form of cold gas or a mixture of cold gas and liquid. Next the liquefied gas 40 as cold gas or a cold gas-liquid mixture is directed into secondary heat exchanger 152. As a result of passing through secondary heat exchanger 152, liquefied gas 40 is completely converted to gas through heat of vaporization, generating waste gas.

Another step in the method involves back regulating the pressure in primary and secondary heat exchangers 148, 152 to both maintain the proper phase of liquefied gas 40 and prevent conversion to a solid phase by avoiding the triple point or other condition conducive to solid formation. In the present embodiment in which liquefied gas 40 is CO₂, the solid phase is dry ice. Formulation of dry ice is disadvantageous as it will freeze the operation of the heat exchanger 146. Additional advantages of back regulating the pressure in conjunction with the use of primary and secondary heat exchangers 148, 152 are (1) enhanced ability to extract as many BTUs as possible from the heat of vaporization to operate fan 162 and (2) increased dwell time in the heat exchanger 146, allowing as much heat to be removed from air 64 as possible for increased cooling efficiency.

Once waste gas has been generated, the waste gas is carried via waste gas conduit 154 to fan motor 160 where it powers fan motor 160, turning fan 162. When fan 162 turns initially, it blows air 64 through fan screen 163, because air 64 has not yet been cooled. Blowing air 64 through fan screen 163 creates negative pressure in the delivery unit 138, thereby causing air 64 to be drawn from the outside (e.g., from chamber 78) into delivery unit 138 across secondary heat exchanger 152. At this point, air 64 may be quite warm above 32.22° C. (90° F.). When air 64 is drawn across secondary heat exchanger 152, the temperature of secondary heat exchanger 152 is lower than that of air 64, thereby lowering the temperature of air 64, creating partially-cooled air 164. Negative pressure continues to work, drawing partially-cooled air 164 across primary heat exchanger 148. Containing liquefied gas-cold gas mixture, primary heat exchanger 148 is cold in the range of about negative 32.22° C. (negative 26° F.) to about 25.56° C. (78° F.). When partially-cooled air 164 is drawn across primary heat exchanger 148, the temperature of primary heat exchanger 148 is lower than that of partially-cooled air 164, thereby lowering the temperature of partially-cooled air 164 even further, creating cooled air 264. Negative pressure from the operation of fan 162 continues to work, drawing cooled air 264 through fan 162 and fan screen 163 into chamber 78. Allowing air 64 to pass through both the primary and secondary heat exchangers 148, 152 provides for increased cooling efficiency.

The process is continually repeated, lowering the temperature of chamber 78 to about 35° C. (95° F.) or below. In an embodiment in which life support system 1 is equipped with a thermostat in communication with tank array valve 178, self-operating cooling system 16 may operate intermittently, maintaining the desired temperature as indicated on the thermostat (not shown).

The method of the present invention also provides for repair of defective components of self-operating cooling system 16. The method comprises maintaining a cache of replacement parts for the various components of self-operating cooling system 16, such as fan motor 160, regulator 150, expansion valve 144 and back pressure regulator 156. The method comprises determining whether self-operating cooling system 16 is experiencing operational difficulties. This determination is made by monitoring gauges 174, collecting readings from the gauges 174 (e.g., pressure readings) and comparing the readings to a trouble-shooting guide or checklist. The trouble-shooting checklist sets out individual readings or combinations of readings, indicating that a certain component may be defective. Once an individual reading or combination set forth on the checklist matches a reading in the field, the defective component so identified can be replaced using the quick-connect type connections and the first and second standard orifices for inlet and outlet connections.

Thus, the components of the cooling circuit 34, 134 work in conjunction with each other to effectively cool a sealed or substantially sealed area (e.g., chamber 78) without electrical, gasoline or other auxiliary power by exploiting evaporation and heat of vaporization of liquefied gas 40 to power the fan motor 60, 160 and fan 62, 162. By running without electrical or gasoline power, the potential for failure is limited. In addition, in an emergency situation, electrical or gasoline power may not be available and even if they were, conditions may make their use dangerous. Cooling circuit 34, 134 is of minimal size to make the self-operating cooling system 16 logistically feasible in mine refuge housing 2. In addition, the components of the cooling circuit 34, 134 may operate on a limited volume of liquefied gas 40.

While the embodiments of the life support system 1 are described herein as used in the underground mining environment, life support system 1 and self-operating cooling system 16 may be adapted to provide shelter, cooling and/or dehumidification in situations where power is not available. One only need think of the recent natural disasters to envision a multitude of uses for the present invention. The embodiments of self-operating cooling system 16 described herein may be used for cooling and/or dehumidification in smaller areas where power is not available or should be conserved, e.g. campers, sleeper cabs, tents, etc.

In understanding the scope of the present invention, the term “comprising” and its derivatives, as used herein, are intended to be open-ended terms that specify the presence of the stated features, elements, components, groups, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, and/or steps. The foregoing also applies to words having similar meanings such as the terms, “including”, “having” and their derivatives. The terms of degree such as “substantially”, “about” and “approximate” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. For example, these terms can be construed as including a deviation of at least ±5% of the modified term if this deviation would not negate the meaning of the word it modifies.

While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other can have intermediate structures disposed between them. The functions of one element can be performed by two, and vice versa. The structures and functions of one embodiment can be adopted in another embodiment. It is not necessary for all advantages to be present in a particular embodiment at the same time. Thus, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. 

1. A life support system, comprising: a refuge housing; and a cooling system operatively associated with the refuge housing, the cooling system having a supply of liquefied gas and a cooling circuit, the supply of liquefied gas being operatively associated with the cooling circuit, the cooling circuit comprising a heat exchanger, a fan motor and a fan operatively associated with the fan motor, and a first conduit connecting the heat exchanger to the fan motor, the fan motor being driven by waste gas generated through a phase change of the liquefied gas in the heat exchanger.
 2. The life support system of claim 1, wherein the heat exchanger comprises a primary heat exchanger and a secondary heat exchanger.
 3. The life support system of claim 1, wherein the liquefied gas is carbon dioxide.
 4. The life support system of claim 2, wherein the primary heat exchanger and the secondary heat exchanger are arranged in series.
 5. The life support system of claim 1, further comprising a carbon dioxide scrubbing system including a plurality of chemical cartridges for removing the carbon dioxide in air.
 6. The life support system of claim 5, wherein the carbon dioxide scrubbing system comprises a scrubber motor operatively associated with a blower, a second conduit connecting the scrubber motor to the heat exchanger, the scrubber motor being driven by the waste gas.
 7. A cooling system comprising: at least one tank of liquefied gas; a cooling circuit connected to the at least one tank by a supply conduit for supplying the liquefied gas to the cooling circuit, the cooling circuit comprising a heat exchanger configured to convert the liquefied gas to waste gas, a fan and a fan motor powered by the waste gas to turn the fan; a delivery unit having a fan port and at least one air port, the delivery unit housing the heat exchanger, the fan and the fan motor; and the fan motor and fan being configured to draw air through the at least one air port and through the heat exchanger and blow cooled air out the fan port.
 8. The cooling system of claim 7, wherein the heat exchanger comprises a primary heat exchanger and a secondary heat exchanger.
 9. The cooling system of claim 8, wherein the primary heat exchanger and the secondary heat exchanger are arranged in parallel.
 10. The cooling system of claim 8, wherein the primary heat exchanger and the secondary heat exchanger are arranged in series.
 11. The cooling system of claim 7, further comprising: a back pressure regulator, the back pressure regulator being disposed between an outlet end of the heat exchanger and the fan motor.
 12. The cooling system of claim 7, further comprising an expansion valve, the expansion valve being disposed between an inlet end of the heat exchanger and the at least one tank.
 13. The cooling system of claim 7, wherein the at least one tank comprises a tank array.
 14. The cooling system of claim 7, wherein the fan motor and the fan are not connected to a conventional power source.
 15. The cooling system of claim 7, wherein the liquefied gas is carbon dioxide.
 16. A method of cooling a confined area without a conventional power source, comprising: supplying a cooling circuit with liquefied gas from at least one tank set at a first pressure, the cooling circuit comprising a heat exchanger; causing the liquefied gas to expand, resulting in expanded liquefied gas; allowing the expanded liquefied gas to convert to waste gas in the heat exchanger; using waste gas to turn a fan, thereby drawing air from the confined area across the heat exchanger, creating cooled air; and using the fan, blowing the cooled air into the confined area.
 17. The method of claim 16, further comprising: evaluating a thermodynamic property of the confined area to calculate a result; and using the result to set the first pressure for the at least one tank.
 18. The method of claim 16, wherein using waste gas to turn a fan comprises supplying waste gas to a fan motor operatively associated with the fan.
 19. The method of claim 16, wherein: the heat exchanger comprises a primary heat exchanger and a secondary heat exchanger; and drawing air from the confined area across the heat exchanger comprises drawing air from the confined area across the secondary heat exchanger, creating partially-cooled air, and drawing the partially-cooled air across the primary heat exchanger, creating cooled air.
 20. The method of claim 16, wherein the cooling circuit comprises a pressure gauge and further comprising: monitoring the pressure gauge for a reading; comparing the reading to a trouble-shooting guide for the cooling system to make a determination; using the determination to identify a defective component of the cooling system; and replacing the defective component. 